Digital Accompaniments 1: Changing Tempos and
other Transformations. This presentation by Terry B. Ewell addresses
ways to change tempos in audio and MIDI files. It also addresses
changes in instrumentation and methods for creating MIDI files. BDP
#279, www.2reed.net.
[Music: Hummel Bassoon Concerto]
Welcome, I am Terry Ewell. This video is made during the height of
COVID 19, Coronavirus, epidemic in the USA. Many music teachers are
struggling with how their students can continue to perform with
accompaniments at a time of social distancing or even quarantines. This
video and the following two videos present solutions that I am
currently employing with my students.
Now undoubtably many teachers are having accompanists record themselves
and then have students practice or even produce recordings to those
accompaniments. However, it is far more useful to have a MIDI files as
the sources of the accompaniment rather than audio files such as those
in wav, aif, or mp3 formats. If at all possible, have your accompanist
record a MIDI file. This is far more useful than the audio file for
accompaniment purposes. Let’s demonstrate the reasons for this.
Tempo Changes: Audio vs. MIDI
Direct recordings of acoustic piano can be unsatisfactory for several
reasons. The audio quality of pianists recording in their homes
may yield poor results.
For instance, this is a recording I made with a grand piano in my home.
[musical example, Pierné Concertpiece]
Clearly this is far from studio quality.
Next, requiring the accompanist to record at multiple tempos is
fatiguing. Although it is possible to change the tempos of audio files
to save the pianist this effort, the results are also less than ideal.
For instance, let me show you how to change tempos without altering the
pitch.
Audacity is an open source software readily available that will change tempos without changing the pitch.
OK, so in order to alter the file go to effects, change tempo:
“change tempo without changing pitch.” Percent, let’s
do 200 percent. OK, let it process, alright. Let’s listen to this.
[musical example, Pierné Concertpiece]
However, the audio quality degrades the original file even more since
each note’s sound wave is slightly clipped to create the faster
tempos. Here again is the original file sample, followed by samples at
tempos 62 and 92.
[musical examples, Pierné Concertpiece]
The further removed the audio file is from the original tempo the worse the quality will be.
MIDI files, however, do not suffer from the same loss of quality. Let
me give an overview of how the MIDI files are created and then a
demonstration of changes made to the files.
How are MIDI files created?
In the 1990s I recorded hundreds of accompaniments for my students and
to share with the double reed community. Entering the data by hand
would take far too long in a MIDI sequencer such as Aria Maestosa.
Instead, I recorded the accompaniment at a slow tempo—one that I
can sight read with reasonable accuracy. I didn’t have time and
still don’t to practice each accompaniment for the hours required
to master it at tempo. So, recording MIDI files at the slower tempo is
the perfect solution. I set a metronome or click track when I make the
recording.
For almost 20 years I have used Yamaha Clavinovas to generate the MIDI
files. This could also be done with a MIDI keyboard connected to a
computer and music program such as Finale.
Changing the Tempo in MIDI
There are several programs that can be used to change tempos in MIDI
files. Currently I find MuseScore 3 to be the best for my purposes.
I first import the file into MuseScore. Here, for example, is a file
that I was working on today for a student. Then I delete the tempo
indication. I don’t know why, but just altering this tempo
indication won’t make the changes. After deleting the original
tempo indication I add a new indication. Add—Text—Tempo
Marking. Oh, I forgot that I have to select the first note.
Add—Text—Tempo Marking. Once I have the tempo marking here,
I can put in the tempo that I would like to have.
Please understand that the score not correctly notated. The notation imported in here is nothing like it should appear.
[musical example, Pierné Concertpiece]
That is tediously slow, isn’t it? It says “80” here.
Well, why don’t we double the speed here, 160, let’s see
how that sounds.
[musical example, Pierné Concertpiece]
OK, so that might be a good practice tempo. I would take out my
metronome and figure out what tempo that is while this is playing.
Let’s even make it twice as fast.
[musical example, Pierné Concertpiece]
So, that is much closer to performance tempo. I can then export that to
an mp3. As you can see I have some files in here and I always give the
tempo marking indication in the file name so that I know what it is.
You can see here that it is very easy to export a number of different
tempos, practice tempos as well as up to performance speed. This is
much quicker that having to play the part over and over again. In
addition, the quality of each version is the same. Here MuseScore
generates mp3 files that sound just as good whatever speed they are at.
That is quite different than audio files that were manipulated to get
different speeds.
Instrumentation Changes in MIDI
Another great advantage to the MIDI files is that changing the
instrumentation is easy. For instance, I prefer the Baroque
accompaniments to have a harpsichord sound. This, for instance, is a
file that I have for the Besozzi Sonata. I have some starting notes and
then both the bassoon and harpsichord enter here.
[musical example: Besozzi Sonata]
OK, but let’s say I didn’t harpsichord. Let’s say I
wanted something else. Go to view, mixer… and that brings up our
mixer. Let’s say I wanted vibraphone to play this instead!
Let’s hear how it sounds with vibraphone.
[musical example: Besozzi Sonata]
Not as good. I think I will switch that back to harpsichord. That was
definitely not my preference for Baroque music. Oops, harpsichord is
off of your screen but I did manage to make the change there.
So, in conclusion, if at all possible, have your accompanist record a
MIDI file. Recordings rendered as MIDI files offer the most
flexibility for practice files. This is far more useful than the audio
file for accompaniment purposes.
[Music: Hummel Bassoon Concerto]